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| Wont start... Weak spark HELP! https://www.slantsix.org/forum/viewtopic.php?f=28&t=62449 |
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| Author: | Blackhawk23 [ Thu Jun 07, 2018 8:48 am ] |
| Post subject: | Wont start... Weak spark HELP! |
This Forum has been a huge help in my Slant six Adventures, and I am hoping someone can help me now. I recently replaced a head gasket on a 84 D150 and now it won’t start. The battery is good, the plugs are hooked up correctly and getting spark, I didn’t move the distributor so timing should be fine. When I had everything back together and went to start it, my buddy bumped the fuse box and caused some sparks. The culprit was a light blue wire under the dash that was hitting metal and sparking. I have isolated that wire, but haven’t been able to figure out where it goes. It comes from the fire wall with all the other wires. It is definitely getting fuel. Compression is fine. The spark is orange though, not blue. There seems to be not enough voltage at the coil at only 5.5 bolts and going down to 4.5 when cranking. I tried a new could, but that didn’t do it. Replaced the ballast resistor but no luck there. Replaced the fusible links off the battery cable. I don’t think it’s that blue wire, but I could be wrong. I have scoured the wiring diagrams and can’t figure out what that’s for or where it goes. Any ideas? I have done my best but I just can’t figure it out. |
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| Author: | DusterIdiot [ Thu Jun 07, 2018 5:22 pm ] |
| Post subject: | Re: Wont start... Weak spark HELP! |
I would look closely at the schematic and your ignition switch... not sure on the late trucks, but on the 70's mopars usually yellow was power to the ignition switch, and light blue went from ignition on to the ballast resistor and beyond in the ignition circuit... |
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| Author: | Blackhawk23 [ Thu Jun 07, 2018 7:28 pm ] |
| Post subject: | Re: Wont start... Weak spark HELP! |
For some reason the ballast resistor only has one of the ignition wires going to it. It has the wire going to the + on the coil on one side, and the other has the one wire going to the ECU and the other going up into the main harness somewhere (I’m assuming it makes it’s way to the ignition switch). Even harder to tell because it is red wire that was put in by previous owner so idk what color it was originally. However, it was this way before head gasket repair and it started anyway. I replaced the ECU, coil, and wiring harness for all that today and put it just how it was. And somewhere in doing that, I lost spark completely. Testing the harness that connects to the ECU, I had good ground and battery voltage where I was supposed to. Ballast resistor is good. Apparently it is an issue with the wiring to the electric distributor. Going to replace the distributor and give it a shot I guess. Fingers crossed. If that doesn’t do it, my days as a Slant Six Owner May be numbered haha |
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| Author: | Blackhawk23 [ Mon Jun 11, 2018 11:02 am ] |
| Post subject: | Re: Wont start... Weak spark HELP! |
Well... replaced distributor and I have spark again. Cranks the engine and she started up for about two seconds and then died and wouldn’t start again. Any ideas? After cranking for about 5 seconds, the spout in the center of the carb is dumping fuel into the carb (maybe too much). I’m thinking that could be the cause and it’s flooding it, but I don’t know why it’s doing that or how to fix that. All ignition electronics are brand new now. So it’s gotta be carb or vaccuum I’m guessing. |
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| Author: | DusterIdiot [ Mon Jun 11, 2018 4:52 pm ] |
| Post subject: | Re: Wont start... Weak spark HELP! |
Quote: the spout in the center of the carb is dumping fuel into the carb (maybe too much) If it's the tube that goes to the top of the carb, that's the bowl vent... that means either the floats have sunk or the needle and/or seat have failed, or the tab on the float isn't set right and ultimately letting the carb bowl fill to capacity with raw gas and then purge it into the engine... You don't want that to keep happening as it will wash the cylinder walls down and you will need a rebuild sooner than later... That being said, if it's dumping that much gas into the manifold and you can't get it to light for more than 5 seconds... I would suspect there are other problems with the air fuel ratio and possibly the manifold gaskets... So if you get it to start for 5 seconds and pull the throttle all the way open does it still keep running or does it still die? Do you have fuel leaks at the carb base gasket or under the manifold where it meets the head? |
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| Author: | Blackhawk23 [ Mon Jun 11, 2018 6:31 pm ] |
| Post subject: | Re: Wont start... Weak spark HELP! |
I looked everywhere and couldn’t find what that tube was for. Forgive me as I don’t usually work on carbureted engines (I’m being reminded why haha), but this is to help out a friend. If that’s the vent then that must be the root of the problem because there is way to much fuel coming out of it. It runs first thing in the morning when I crank it for 2-3 seconds (about how long it takes for fuel to spray out of the vent and into the carb) which is when it dies. It doesn’t run at all starts after that. Even if I wait about 8 hours or so. I don’t try too much more that day because I was certain it was flooded after all that gas. When I replaced the head gasket, I replaced the manifold gasket along with all the studs and the appropriate washers etc (will a lot of research on this forum as to what was best). There are no other fuel leaks. I haven’t had the chance to mess with the throttle because it only gets that’s one startup in the morning. I can try holding the throttle down on tomorrow’s startup if that would give us more information. It is a remanufactured carb which I know aren’t preferred, but it’s what was on there and running before the other repairs so I figured it would still get her running for now at least. If she doesn’t pick up in the morning then I can look into the float and start working at the carb. Idk how long it’s been on there so maybe it just needs to go. |
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| Author: | Blackhawk23 [ Mon Jun 11, 2018 9:18 pm ] |
| Post subject: | Re: Wont start... Weak spark HELP! |
To be clear, I was referring to the spout that’s actually inside the carb at the top. I can send a pic in the morning. I really appreciate the help |
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| Author: | Brian [ Thu Jun 14, 2018 4:05 pm ] |
| Post subject: | Re: Wont start... Weak spark HELP! |
Check the needle and seat at the fuel inlet on the carb. This is a Holley 1945 right? You might have to pull the carb off and dig into it. Float may be set way off. |
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| Author: | Blackhawk23 [ Thu Jun 14, 2018 9:35 pm ] |
| Post subject: | Re: Wont start... Weak spark HELP! |
Yes. Holley 1945. Im going to pull it apart when I get back home in a few weeks. |
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